A plasma arc utilizing apparatus like a plasma arc cutter includes a power supply unit therefor. In one example of such power supply unit, an AC voltage is converted into a DC voltage, which is then converted to a high-frequency voltage by an inverter. The high-frequency voltage is then transformed by a transformer, and the resulting transformed high-frequency voltage is rectified and smoothed into a DC voltage. The ultimate DC voltage is applied between a torch and a workpiece, e.g. a material to be cut by a plasma arc cutter, whereby an arc is generated between them. A compressed gas, e.g. compressed air, supplied from a compressor is jetted from the torch toward the workpiece and is ionized by the arc generated between the torch and the workpiece to thereby cut the workpiece. The use of an inverter in such plasma arc cutters can eliminate the need for using a large-sized transformer and a reactor in the power supply unit, and, therefore, the power supply unit can be small in size. Since the size of the power supply unit can be made smaller, the compressor can be placed also in a housing in which the power supply unit is placed. Thus, plasma arc utilizing apparatuses as a whole can be small in size. An example of such air plasma arc cutter is disclosed in Japanese Examined Patent Publication No. HEI 6-38985 published on May 25, 1994.
When it is operating, a compressor vibrates significantly. Accordingly, when a compressor is mounted in a housing, in which also a power supply unit is disposed, it is necessary to take measures for preventing vibrations from being transmitted from the compressor to the housing as much as possible. One possible measure is to use vibration absorbing rubber. Bolts may extend through the lower panel of the housing, legs of the compressor and vibration absorbing rubber members, with the rubber members interposed between the lower panel and the respective legs of the compressor. Nuts are screwed onto the bolts to thereby secure the compressor to the lower panel of the housing. Vibrations generated by the compressor are absorbed by the respective rubber members, so that noise, which would be caused by vibrations, can be suppressed to some extent. It may also reduce, to some extent, vibrations which would otherwise be transmitted to printed circuit boards with electronic components forming the power supply unit disposed thereon.
With the above-described vibration preventing arrangement, however, vibrations produced by the compressor are transmitted through the bolts to the housing and to the printed circuit boards in the housing through the housing. Accordingly, it is impossible to completely suppress transmission of vibrations. When the printed circuit boards vibrate, wiring of electronic components on the boards could be cut, which would cause failure of the power supply unit. Further, it is troublesome to secure the legs of the compressor by bolts and nuts.
Accordingly, an object of the present invention is to provide a plasma arc utilizing apparatus with sufficiently suppressed vibrations of a compressor.